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<h1>Query Filtering</h1>

<p>Query filtering prevents queries that match a certian pattern from being run at all.  There are often certain queries that will bring the entire database to its knees.  A common use for query filtering is to identify those queries and prevent them from being run.</p>

<p>For example, <i>select * from hugetable where id=100</i> might be fine...</p>

<p><img src="../images/query-allowed.png"/></p>

<p>...but <i>select * from hugetable</i> without a where clause might crush the database.</p>

<p><img src="../images/query-rejected.png"/></p>

<p>SQL Relay can be configured to allow one and reject the other.</p>

<p>A complete descripton of query filtering with example configuration files is given <a href="../admin/configguide.html#filtering">here</a>.
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